Lectin carbohydrate interactions mediate feeding selection in the Manila clam Ruditapes philippinarum

Filter-feeding bivalves represent ecologically and economically crucial organisms in coastal ecosystems and mariculture systems, with their feeding behavior profoundly modulating nutrient biogeochemical cycling and aquaculture productivity. Despite the recognition of particle selection in bivalves, the intrinsic mechanisms underlying this process remain largely elusive. This study uncovers a sugar-code mechanism governing particle selection in the Manila clam Ruditapes philippinarum via mucosal lectin-carbohydrate interactions. The Manila clam exhibited strong feeding selectivity, showing a 100% sorting efficiency for Thalassiosira weissflogii over Platymonas subcordiformis . Such preferential ingestion was tightly associated with distinct cell-surface glycosylation signatures between the two phytoplankton species. Specifically, T. weissflogii was highly enriched in glucose and galactose residues, while P. subcordiformis contained significantly lower abundances of these two monosaccharides but higher levels of arabinose and xylose. Lectin-mediated blockade of glucose and galactose residues eliminated feeding preference and reversed ingestion bias. Furthermore, mucosal proteomics analysis revealed abundant galectins and C-type lectins in clam feeding tissues, with a novel mucosal lectin gene ( RpML ) significantly downregulated upon glucose blockade. Our results demonstrate that mucosal lectin-glucose/galactose recognition mediates pre-ingestive selection, advancing coastal biogeochemical theory and providing a molecular foundation for optimized bivalve aquaculture diets.